Q I graduate in June and need a car for my new job. I’d prefer a hire purchase or a personal contract plan to buying outright. I understand a personal contract would not be considered a credit deal by a mortgage provider. Any advice? – RB from Derby

A You have three options: a conventional bank loan, hire purchase or a personal contract plan. A bank loan has the advantage that you own the car outright from the start, and although you say you would rather avoid this as a new graduate you may be able to negotiate a good deal.

With hire purchase you pay a deposit then borrow the remainder from a finance company, making repayments plus interest over an agreed period (anything from one to five years). The main disadvantage is that annual interest can exceed 10% and if you default on payments the retailer can repossess the car.

A personal contract purchase plan is similar to hire purchase in that you pay a deposit and then monthly payments but it is essentially a rental agreement. At the end of the contract you can choose to hand the car back, or make a final balancing payment to keep it. The agreement may also place restrictions on mileage.

Dealers often make more money on payment plans than on the sale of the car, so don’t fall for the sales patter, ensure you shop around, check the small print and be aware you can negotiate on the monthly payment rates. Try price comparison websites such as www.moneysupermarket.com or www.askaprice.com.

As regards a mortgage application, providers will consider all loans, credit deals and outgoings in the form of monthly payments before making an advance.

Q I’m having trouble changing a £1.50 headlight bulb on my 1999 Porsche Boxster. The unit on the driver’s side will not come off. How can I save a trip to the dealer? – POR from Blackpool

A Remove the plastic nut that keeps the boot lining in place (in a rear-engined car the boot is at the front), then twist off the rubber plug protecting the locking mechanism. Under this you’ll find a hexagonal hole.

Use the hexagonal key that should have come with the Porsche toolkit and turn it about a quarter of a rotation towards the back of the car to unlock the lamp, then ease it out.

If you’re having trouble, it may be that your key – which is made from relatively soft metal – has rounded off. Try a screwdriver with a hexagonal attachment and a squirt of WD40. If you still get nowhere, remove the wheel and the plastic wheelarch liner to get a better view of any problem.

Q At 72 I have decided to buy a soft-top sports car for Sunday driving. I like the 2 litre Mazda MX-5 at about £17,000, but my son says a three-year-old BMW Z3 2 litre for £13,000 is a better buy. What would you do? – ED from Leamington Spa

A The MX-5 is the world’s bestselling convertible sports car. It has proved reliable, enjoyable to drive and easy to resell. The latest model is better equipped, more refined and more comfortable.

The BMW Z3 has a reputation as a slightly underpowered “hairdresser’s car”, although the six-cylinder model is more sporty.

A 2003 52-plate Z3 2.2 with a six-cylinder engine and 170bhp would come in at about £13,000. But if you can afford a new MX-5, go for the 2 litre for £17,465. You’ll have a brand-new model and manufacturer’s warranty.

Q We’ve just bought a 2002 VW Golf GTI 150bhp diesel. Its mpg is no more than the low forties, a lot less than our former 115bhp Golf diesel. I’m a reasonably steady driver. Any ideas? – BG from Hull

A An mpg in the low forties does not seem unreasonable for this car.

The official economy figures for your Golf are 39.2mpg on urban roads, 64.2mpg on extra-urban roads and 51.4mpg combined. But official figures seldom reflect the real world and are only useful when comparing cars.

As you describe your driving as “steady”, you’re probably not offsetting the drop in mpg by making the most of your new car’s superior acceleration. If your priority is fuel economy, you need a less powerful car.

E-mail your questions for our experts to carclinic@sunday-times.co.uk or write to Car Clinic, InGear, The Sunday Times, 1 Pennington Street, London E98 1ST. Please give a daytime telephone number. We cannot send personal replies or deal with every letter. Please do not send original documents or SAEs. Advice is offered without legal responsibility.